1. Field of the Invention
The present invention relates to a cartridge library apparatus suitable for use in handling a number of cartridges of magnetic tape in one operation.
2. Related Art
While various kinds of external memory sub-systems are known for implementation in information processing systems such as general-purpose electronic computer systems, a typical example is a cartridge library apparatus that comprises racks accommodating a number of cartridges of magnetic tape (which are hereunder sometimes referred to simply as "cartridges"), a magnetic tape drive unit and a transport mechanism such as an accessor robot for performing necessary jobs such as transport of cartridges between one of those racks and the drive unit and which is capable of providing a large storage capacity.
An example of the means for enabling cartridges to be either unloaded from the cartridge library apparatus or loaded thereinto is described in Unexamined Published Japanese Patent Application No. 80847/1981. The cartridge transfer mechanism described in that patent comprises a disk-shaped member that has one side facing racks and the other side exposed to the outside, with a plurality of cartridge-accommodating cylinders being arranged rotatably and radially on the disk-shaped member. With the aid of those cylinders, the cartridges can individually be loaded onto or unloaded from the racks.
The user of the prior art library apparatus is capable of loading it with only one cartridge at a time and when loading a high volume of cartridges into the apparatus or unloading them for such purposes as processing files on a monthly or yearly basis, the user has to be involved so many times in getting the job done that not only does his workload increase but also the time required to complete the job will be prolonged.